1. Field of the Invention
The present invention relates to a method for fabricating a through-hole interconnection substrate and a through-hole interconnection substrate. More specifically, the present invention is adapted for a high-density three-dimensional packaging of stacking a silicon IC chip and the like or to a contact thereof. The present invention is also adapted for a silicon optical bench for implementing an optical device such as a laser diode, a photodiode and an optical waveguide.
According to the present invention, a metal for a conductor is filled in micro-holes for through-hole electrodes. The through hole electrodes are utilized for interconnecting wiring patterns formed on front and back surfaces of a silicon substrate, to be employed as electrodes or contacts, and to form bumps.
2. Description of the Related Art
An example of a related art technology for filling metal in micro-holes is a molten-metal suction method disclosed in Japanese Patent Laid-Open No. 2002-158191. According to this method, a molten metal is filled in the holes by means of a pressure difference. An example of a method for forming bumps on one surface of a substrate simultaneously with this filling work, is one in which metal layers are formed in the peripheries of openings of the micro-holes, followed by the metal filling by the molten-metal suction method.
In the molten-metal suction method, heat sometimes deteriorates adhesion of a heat-resistant sheet, thus making it impossible to fill the metal fully in the ends of the micro-holes.
Specifically, when the melting temperature of the metal material in use exceeds 350° C. (degrees centigrade) during the filling work, such high temperature is beyond a tolerance of the heat-resistant sheet.